loggers throws multiple warnings

See https://github.com/mlr-org/mlr3/actions/runs/3999684989/jobs/6863883786.

  ── Warning ('test_lgr.R:21'): log to text file ─────────────────────────────────
  [2023-01-24 19:26:35.692] mlr3 <AppenderFile> ~ error in `lg$debug("Subsetting task '%s' to %i rows", task$id, length(train_row_ids), task = task$clone(), row_ids = train_row_ids)`: No method asJSON S3 class: R6
  Backtrace:
    1. mlr3::resample(task, learner, resampling)
         at test_lgr.R:21:2
    2. mlr3:::future_map(...)
    3. future.apply::future_mapply(...)
    4. future.apply:::future_xapply(...)
    6. future:::value.list(fs)
    8. future:::resolve.list(...)
    9. future (local) signalConditionsASAP(obj, resignal = FALSE, pos = ii)
   10. future:::signalConditions(...)

with mlr3 debug

18: [2023-02-08 23:29:30.826] mlr3 <AppenderFile> ~ error in `lg$debug("Learner '%s' returned an object of class '%s'", learner$id, class(pdata)[1L], learner = learner$clone(), prediction_data = pdata, messages = result$log$msg)`: No method asJSON S3 class: R6

Is likely a change in lgr.

mlr-org / mlr3

loggers throws multiple warnings #898